Cigarette smoke has been shown to induce cytochrome P450 (CYP1A1, CYP1B1) and aldo-keto reductase (AKR1C1, AKR1C3, AKR1B10) genes in oral dysplasia and primary oral carcinoma cell lines [37]. Here, CYP1B1 is linked to lip and oral cavity carcinoma.